Full stroke positive feed printing platen



Sept. 1, 1959 2,902,134

J. w. DobswoR'rH FULL STROKE POSITIVE FEED PRINTING PLATEN Filed Nov.15, 1957 2 Sheets-Sheet 1 INVENTOR. JAMES W. DODSWORTH- AGENT Sept. 1,1959 J. w. DODSWORTH 2,902,134

FULL STROKE POSITIVE FEED PRINTING PLATEN Filed Nov. 15, 1957 2Sheets-Sheet 2 mummy .7/ INVENTOR. JAMES w. DODSWORTH" AGENT PatentedSept. 1, 1959 2,902,134 I FULL STROKE Posrrrvn FEEn PRINTING PLATENApplication November 15, 1957 Serial No. 696,877

11 Claims. (Cl. '197-114) The present invention relates to listingcalculating machines and the like capable of recording factors andresults of calculations on work sheets entered around the usual printingplaten of such machines. However, it is to be understood that theinvention may be applicable to other types of machines capable ofrecording data on paper.

Machines of the above type generally incorporate a rotatable papersupporting platen which is automatically and incrementally advanced asan incident to operation of the machine in order to permit listing ofvarious values in sequence along different lines of the work sheet.Usually the platen is also provided-with a twirler knob or the like forrotating the platen in either direction, whereby the same can bemanually advanced or retarded to thread a work sheet into or out of themachine or to provide a relatively large blank space for the purpose ofentering identifying data or thelike. I

Heretofore means for automatically advancing the paper platen usuallyinclude a ratchet wheel and a pawl for advancing the ratchet Wheelwherein the pawl is caused to be automatically withdrawn gradually fromthe active tooth of the wheel while the paper feed stroke is beingeffected. Thereafter a suitable spring tensioned locating means acts toassist momentum of the parts and complete the line space operation.Since a release of the operating pawl from an active tooth of theratchet wheel if occurring too soon would cause an understroking of Ithe platen feed and 'if' held in engagement too long would causeoverthrowing of the feed it is necessary that close manufacturingtolerances and adjustments be maintained in such devices.

Aprincipal object of the present invention is to provide a moresimplified'and improved platen feed means for effecting a full strokepositive line space operation of the paper platen for such machines.

Another object is to provide a line spacing means wherein the operatingpawl will maintain engagement with the ratchet wheel of the platenthroughout the entire active range of platen advancement.

Another object of the invention provides automatic means which at thecompletion of a feeding stroke will act to positively lock the platenagainst an overthrow.

Still another object is to provide means which will act following thecompletion of a full stroke positive feed operation of the platen forautomatically conditioning the feed means whereby the platen maythereafter be manually operated in either direction. r

The manner in which the invention is carried out will be readilyunderstood on reference to the following specification when read inconjunction with the accompanying drawings, wherein: I N

Fig. l is a sectional View illustrating the mechanism for automaticallyadvancing the platen as an incident to a machine operation, the partsbeing shown in normal condition of rest. f

Fig. 2 is a detail view showing the platen feed pawl at the end of aforward stroke and preparatory to effecting a multiple line spaceoperation of the platen.

Fig. 3 is a view similar to Fig. l and with the parts shown justcompleting a full operating stroke of the platen advancing means.

Fig. 4 is a detail view with parts of the platen feed devices shown in aposition taken just at the end of an operation of the cyclic meanstherefor.

Fig. 5 is a detail perspective showing parts of the automatic feeddevices, together with a control knob for manually operating the platenin either direction.

The improved line space device disclosed herein has been shown forconvenience with relation to a printing platen mounted in a shiftablecarriage of a listing calculator of the type such as disclosed in PatentNo. 1,946,572, issued to Loring P. Crosman on February 13, 1934, asmodified-by the disclosure of Patent No. 2,748,916, issued to Harvie J.Duke on June 5, 1956. It will be obvious, I however, that said linespacing device is equally adaptable for operation in conjunction withsuch type machines.

and other printers equipped with either a shiftable or a non-shiftableplaten carriage.

A work sheet or tape having been first inserted into the platen carriage10, between the platen 11 and the.- usual pressure rollers 12, isthereafter advanced around; the platen to bring the desired printingline to proper position relative to the printing hammers 13 by the:manual rotation of a suitable twirler knob 14, in the; well-knownmanner.

Pivotally mounted at 15 within the right and left end framing of thecarriage is a transverse bail 16 held nor-- mally in raised position,against tension of spring 17, by: means of a roller ls fast to therearward .arm of a three: armed ope'rating lever'19. Lever 19 isfulcrumed upon;

forward arm'thereof having engagement with a cam lever 22 fast upon atransverse shaft 23. Also fast upon shaft;

23 is an'arm 24 having link connection 25 with a rock arm 26fast toalrock shaft 27. A reciprocatory forward 7 and return movement of rockshaft 27 is effected either by suitable handoperated lever means, inknown manner, or by motor clutch control means, such as set forth inPatent No. 1,946,572 of reference. During a forward movement of rockshaft 27 the cam 22, through means of arm 26,-link 25, arm 24 and shaft23, will be rocked in a clockwise direction. In the first part of saidmovement of cam 22 the roller 21 is engaged by a high point 22 of thecam provided for the purpose hereinafter described. Thereafter saidroller will follow the falling edge of said, cam to permit a clockwiseoperation of the lever 19, under influence of a spring member 28 securedat one end to an upwardly extending arm of said lever and at theopposite end thereof to a stud 29 secured to the fixed shaft 20. Uponclockwise operation of lever 19 v 32. Said pawl has a lateral lug 33adapted for engaging the teeth of a'ratchet wheel 34, fast to the platenshaft 35,'for effectingrotation of the platen 11, as in the manner to bedescribed. r g

It is desirable that the platen \11 be normally free 'for an operationin either direction by the manual control knob 14. xspe'cial'means areprovided therefore to holdthe feed pawl 32 normally rocked in' aclockwise position I a spring 37. Saidspring is connected to the lowerend portion of the flipper 36 and to astudwhich acts to support a roller38 on'the forward arm ofa locator pawl39,

pivotally supported upon an eccentric stud 40 mounted: in thecarriageend frame. A suitable spring 41. for pawl 39. acts to holdroller 38 in yieldable engagement with the.

teeth of ratchet wheel 34 for holdingthe platen in properrotationalposition. Roller 38 serves also as a stop means for the flipper 36, sothat a cam surface 36 of the flipper.

Will act to support lug 33 of the feed pawl32 .f ree of ratchet wheel34.

During the, above described downward operation of bail 16 the pawl 32moves forwardly with arm 16' and lug 33 moves oil the cam surface 36'and into a full depth of engagement permitted with a selective one ofthe teeth of ratchet wheel 34, as illustrated in Fig. 2. While Fig. 2illustrates the pawl 32 in a position for effecting a two tooth stepoperation of the ratchet wheel. 34, suitable well-known means forlimiting the extent of operation of;

bail 16 may be provided to control a non-operation or one or more stepsof line space operations of the platen. 7 It will be noted at this timethat a portion of lug 33 now extends below a pointed forward end of thecam edge 36' of the flipper 36. Upon a subsequent return movement ofrock shaft 27 the parts earlier described will act to restore roller 18and the bail 16 upwardly, rocking arm 16 ina clockwise direction andreturning thereby feed pawl 32 rearwardly. During such operation lug 33of pawl 32 remains in full depth engagement with theactive tooth ofratchet wheel 34 and will in the present instance, effect a positiverotation of said ratchet wheel for two complete tooth steps of itsmovement in advancing the,plat en,11. In the final tooth step ofoperation lug 33 acts also to engage the pointed end of flipper 36 andimparts thereby a clockwise movement to said flipper against tension ofthe spring 37, for the purpose hereinafter to be described. 7 Operationof the feed devices in advancing the platen for a full stroke ofoperation may materially increase the danger of overthrow thereof andspecialmeans are provided therefore operable under control of the feeddevices topositively lock the ratchet wheel 34 and thereby platen 11 atsubstantially the point of completion of thefeed stroke and prevent anyfarther rotation thereof.

Loosely mounted upon pivot stud of the bail 16 is an upwardly extendinglever 42 having an eccentric stud connection 43 with the arm 16 of saidbail. Mounted at 44 to the lever 42 is a yieldable latch 45 positionednormally by lever 42 out of cooperation with a lug 46 on the rearwardarm of locator pawl 39, earlier described. During the above describedoperation of bail 16 arm 16 thereof in effecting a forward and returnoperation to feed pawl 32 will synchronously therewith effect a forwardand return movement to latch 45. Thus during any multiple toothoperations of ratchet wheel 34 the locator pawl 39 is free as roller 38moves over the teeth of the ratchet wheel. a completion of any finaltooth step of operation of the ratchet wheel 34 and while roller 38moves over a tooth thereof the pawl 45 engages the forward surface oflug 46 and will yield counterclockwise. Just prior to the maximum pointof a return movement of the feed pawl 32 and arm 42, occasioned byengagement of cam edge 22'; with the operating roller 21 in a returnoperation of rock cam 22, roller 38 will have entered a tooth space ofratchet wheel 34 sufficiently to release the forward face of lug 46 fromlatch 45. Upon release from lug 46 latch 45 snaps to a position oversaid lug and will immediately thereby lock the locator 39 and roller38vand .thuseffect The timing is such, however, thatnear roller 21 fromthe cam point 22 ,to permit a slight. retraction of the parts, duringwhich latch pawl 45 is withdrawn from lug 46 and is again at the normalposition of rest shown in Fig. 1.

It will be recalled that at the completion of a feed stroke of operationpawl 32;ho lds flipper 36 rocked in a clockwise direction. During thefinal. retractive move ment of the parts above describedlug 33movesforward slightly and is caused to engage the rearward cam edge of atoothof the ratchet wheel 34. tobe cammed upward- 1y thereby. and abovethe pointed nose of the cam edge 36 of flipper 36. Thus lug 33willimmediately release flipper 36, to counterclockwise'operation by itsspring 37 and cam edge 36' acting on lug 33 restores the feed pawl 32upwardly to normal position and outof-cooperative relation with respectto the ratchet pawl 34, whereby the platen is now again free for manualoperation in either ect on...

. h leIherqhasbeen. shown and described a preferredv en 1bod imentof;the. present invention it Will be obvious that changes in form; and;details of the device may be made by those-skilledin the art,;and it is,therefore, contemplated'to cover; by the appended claims .anysuchmodifications as fall within the true spirit and scope of the in-..

vention atI a m is;

l. In a listing calculating machine or the, like the combinationcomprising a rotatable platen, means for maintaining a paper-strip incontact therewith, a ratchet wheel carried by said, platen, an indexingpawl 00-.

reciprocatory means for releasing the indexing pawl from said engagementwith the controlmember after thecompletion of-said advancing movement,and whereinifollowing said;release the said; control member will acttoautomatically displace the indexing pawl free of engagement with theratchet wheel, whereby to normally permit rotation of the platen.ineither direction.

2. In a, listing calculating machine or the like the combinationcomprising, a rotatable platen, means for maintaining a paper strip incontact therewith, a ratchet wheel carried by said platen, an indexingpawl adapted to maintain engagement therewith throughout an advancingoperation to positively complete an index movement of the ,platen, aspring biased control member having a holding surface adapted fornormally maintaining the index awlfree of cooperation with the teeth;of, said ratchet wheel, and means for effecting a reciprocatoryoperationofsaidindexing pawl for advancing said ratchet wheel, and wherein theindexing pawl upon a forward movement of the indexing stroke is releasedfrom the saidaholding surface into engagement with the teeth of saidratchet wheel, and wherein upon a return stroke thereof for advancingthe ratchet wheel saidindex pawl engages a forward edge of said holdingsurface and will act to move the control member to a position of storedpotential energy, and where,- in following said advancing operation theindex pawl is moved by the reciprocating means to be released therebyfrom the said'forward edge, and wherein the said control memberwillthereupon automatically restore-the-indexing pawl-'free of saidratchet Wheel.

' 3. In a listing calculating machine or the like the combination comprisingua rotatable platen, a ratchet wheel for rotating said platen, anindexing pawl adapted for reciprocatory operation and cooperable withsaid ratchet wheel for advancing the platen, an operating membernormally holding the indexing pawl free of said ratchet wheel, andhaving a cam surface extending from a point outside the peripheraldiameter of said ratchet wheel and terminating in a forward operatingedge at a point intermediate of the root diameter of the ratchet wheelteeth, and means for effecting stored energy in said member, and whereinduring a'reciprocating operation the indexing pawl is released intoengagement with the teeth of said ratchet wheel, and into a cooperativerelation with the said forward edge, and will thereafter during theindexing operation of the ratchet wheel effect a displacement of theoperating member to an active position of stored energy, and wherein acontinued movement of the indexing pawl thereafter releases the saidenergized operating member for camming said indexing pawl out ofengagement with the teeth of said ratchet wheel.

4. In a listing calculating machine or the like the combination having arotatable platen, means for maintaining a paper strip in contact withsaid platen, a ratchet wheel carried by said platen, means for effectinga positive advancement of said platen for a full in ement of movementincluding an indexing pawl having uniform engagement with said ratchetwheel throughout an indexing stroke of its movement, means forreciprocating said indexing pawl, said means being adapted to normallymaintain said pawl in a position intermediate of the indexing stroke ofmovement, and a control means adapted in such intermediate position ofsaid pawl for holding said pawl free of engagement with the said ratchetwheel, whereby to permit normallv a rotation of said platen selectivelyin either direction.

5. The invention according to claim 4 and wherein the said control meansinclude a spring biased member having a cam edge extending from a pointbeyond the peripheral diameter of the ratchet wheel and terminating in aforward control edge at an opposite end thereof at a point intermediateof the root diameter of the teeth of said ratchet wheel, and wherein theindexing pawl during an indexing operation of the ratchet wheel engagessaid forward edge and will displace the spring biased member against thetension of its spring, and wherein the reciprocating means is adaptedfor thereafter returning the indexing pawl from its extreme advanceposition of index movement to the said normal intermediate positionthereof, and wherein during said return movement the indexing pawl iscammed partially along a tooth of the ratchet Wheel to release theindexing pawl from the said forward control edge and to cause thereby anautomatic spring operation of said control means, whereby the said camedge thereupon restores the indexing pawl out of cooperation with theteeth of the ratchet wheel.

6. In a listing calculating machine or the like the combination of arotatable platen, means for maintaining a paper strip in contact withsaid platen, a ratchet wheel carried by said platen, means for effectinga full stroke of positive advancement to said platen including anindexing pawl adapted for maintaining uniform engagement with an activetooth of the ratchet throughout the advancing operation, meansengageable with successive teeth of said ratchet and adapted forlocating the ratchet yieldably in adjusted positions, operating meansfor effecting reciprocatory movements of the indexing pawl, and normallyineffective latching means for said locating means, said latching meansbeing adapted for operation by said reciprocating means in unison withoperations of the indexing pawl, and wherein said latching means upon acompletion of the platen advancing stroke movement of the indexing pawlis brought into locked engagement with the said locating means to thuslock the ratchet wheel against a farther rotation, and thereby effect apositive over-rotation check of the platen feed.

7. The invention according to claim 6 and wherein the said reciprocatingmeans will thereafter impart a retrograde movement to the indexing pawl,whereby to return said pawl from the full stroke platen advance positionback to the normal start position of said pawl and to concurrentlytherewith effect disengagement of said latching means from the saidlocating means, whereby the ratchet wheel is freed for any subsequentrotation as effected independently of the said platen advancing means.

8. In an apparatus of the character described the combination having arotatable paper platen, a ratchet wheel for effecting feeding operationsthereof, an indexing pawl engaging the ratchet wheel for a full indexingstroke of movement, a spring biased member adapted in normal positionfor holding said indexing pawl free of engagement with the ratchet wheelwhereby to permit a manual rotation of the platen in either direction,resilient locator means for maintaining the platen in any adjustedposition, a latch pawl cooperable with said locator means and normallyinactive thereof, and means for concurrently effecting a reciprocatoryoperation of the indexing pawl and of the said latch pawl, and whereinthe indexing pawl upon movement in one direction is released from thesaid holding member to effect engagement with an advanced tooth of saidratchet wheel and to also condition said indexing pawl to an effectiveposition relative to the said holding member whereby in a return fromsaid movement the indexing pawl effects both an advancing operation ofthe ratchet wheel and a displacement of the said holding member to anactive position of potential energy, and wherein the reciprocating meansin effecting terminal movement of the ratchet wheel effects engagementof the said latch pawl with the said locator means and will therebyprovide for a positive over-rotation check of the feeding operation.

9. The invention according to claim 8 and including operating means foreffecting a subsequent partial stroke movement of the reciprocatingmeans, whereby to efiect a release of the latch pawl from the saidplaten locator means and to concurrently therewith release the saidindexing pawl from the holding member, and wherein said holding memberwill thereupon act to restore the said indexing pawl free of engagementwith the ratchet wheel.

10. In a machine of the character described having a rotatable platen, aratchet carried by said platen, and an indexing pawl for advancing saidratchet, the combination of means responsive to an operation of saidmachine for reciprocating said pawl, said means normally holding saidpawl at a position intermediate of an extremity of its travel, and acontrol member cooperable with the pawl in said intermediate positionfor normally maintaining said pawl free of engagement with the teeth ofsaid ratchet, whereby normally to permit a manual rotation of saidplaten in either direction, and wherein during reciprocating operationthe indexing pawl is released from said control member to engage anadvanced tooth of the ratchet, and to thereafter effect positiveadvancement of the ratchet a full increment of selected movement, andwherein during a completion of said movement the indexing pawl will actto displace the said control member to an active condition of storedenergy, and wherein the reciprocating means thereafter effects arestoring movement of the indexing pawl to its intermedlate positionwhereby to release the said pawl from said control member and therebycause operation thereof, and wherein during said operation the controlmember automatically restores the indexing pawl to normal position andfree of the teeth of said ratchet.

11. In a machine of the character described having a rotatable platen, aratchet carried by said platen and a feed pawl for advancing saidratchet, the combination 7, of means responsive to an operation of saidmachine for reciprocating'said pawl, said means being adapted forholding said pawl normally at a position intermediate of an indexingmovement, a control member adapted with the feed pawl in saidintermediate position for holding said pawl free of engagement withtheteeth of said ratchet, so that the platen is normally free forrotation in either direction, a normally resilient locator, for engagingsuccessive teeth of the ratchet to hold the platen in adjustedpositions, and a springlatch operable with the feed pawl, said latch insaid intermediate position of the feed pawl being held free ofengagement with the said locator, and wherein near the end of a platenadvancing. movement said'latch is moved'into yieldable engagement withthe said locator, andwherein at substantially a terminal advancingmovement of the feed pawl said'latch snaps into 8e, engagement with thesaid locator to positively lock the said locator and'thusalso rotationofsaid ratchet against an overfeed movement, and wherein a continuedoperation of the reciprocating means thereafter restores the saidfeed'pawl to.its intermediate position, and will concurrently therewithrelease the said latch from the said' locator, andwherein during thesaid restoring operation the said control member acts to automaticallyrestore the feed pawl free of engagement with the ratchet, wherebyfollowing such indexing operation the platen is again free for rotationin either direction.

References Cited in the file of this patent UNITED STATES PATENTS2,797,791 Kuhne July 2, 1957

